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National Advisory Committee for Aeronautics, Technical Notes - Measurement of Heat Transfer in the Turbulent Boundary Layer on a Flat Plate in Supersonic Flow and Comparison with Skin Friction Results

Local heat-transfer rates on the surface of a heated flat plate at
zero incidence to an air stream flowing at Mach numbers of 1.69 and 2.27
are presented. The Reynolds number range for both Mach numbers was 1
million to 10 million. Surface temperatures were maintained near recov-
ery temperature. It was found that the variation of heat transfer with
Mach number was in agreement with previously reported variations of
directly measured skin friction with Mach number on unheated bodies. The
variation with Mach number of the average skin—friction coefficient, as
determined from impact-pressure surveys, was in agreement with that from
other momentum loss measurements but differed from the variation obtained
from directly measured skin friction as reported by others.

It is difficult, on the basis of available basic heat-transfer data
pertaining to the turbulent compressible boundary layer, to make valid
comparisons of heat transfer and skin friction for equivalent flow con-
ditions. This situation is partially due to the lack of experimental
information, and also to the fact that the correlation of the available
heat-transfer data on a length Reynolds number basis requires information
about the development of the turbulent boundary layer which has not been
adequately defined in many of the experiments. Turbulent boundary layers
may be induced artificially with trips or may occur naturally after an
initial laminar and transitional region; and since the process of develop-
ment of the boundary layer to a fully turbulent character is not ade-
quately understood, it is necessary to establish that the boundary layer
is fully turbulent over the test region and then to fix an effective
Reynolds number with which to characterize the actual flow. This effec-
tive Reynolds number would then allow correlation of the various heat-
transfer tests. It is important to obtain sufficient information to
establish an effective Reynolds number when tests are made with small
models.